1. EGR 334 Thermodynamics Chapter 3: Section 1-5
Lecture 06:
Evaluating Properties
Quiz Today?

2. Today’s main concepts:
Number of properties needed to set simple compressible system.
State properties: Temperature, Pressure, Specific Volume
Phase and Quality.
Given two properties of a pure compressible substance, find other state properties.
Using the Thermodynamic Property tables.
Reading Assignment:
Read Chap 3: Sections 6-8
Homework Assignment:
From Chap 3: 5, 7, 10, 29

3. A contents of a glass containing water and ice?
Sec 3.1.1: Phase and Pure Substance
Pure Substance: a substance that is uniform and invariable in chemical composition.
May each of these be considered a pure substance?
A jar of honey, water, oil, and ice topped with air?
Oil
Ice
Water
Honey
Air
Helium gas
in a tank?
Yes No
A contents of a
glass containing
water and ice?
Atmospheric
air?
Yes
Yes…maybe

4. Bottle Contents : Air (N2, O2, ect.) Homogeneous chemical composition?
Sec 3.1.1: Phase and Pure Substance
Phase: Matter which is homogeneous throughout in both its chemical composition and physical structure.
Bottle Contents : Air (N2, O2, ect.)
Homogeneous chemical composition?
Homogeneous physical structure?
Bottle : Glass
Homogeneous chemical composition?
Homogeneous physical structure?
Cap : Aluminum?
Homogeneous chemical composition?
Homogeneous physical structure?

5. Pure substances can exist in multiple phases.
Sec 3.1.1: Phase and Pure Substance
Phase: Matter which is homogeneous throughout in both its chemical composition and physical structure.
- Gaseous Phase
- Liquid Phase
Solid Phase
Pure substances can exist in multiple phases.
Pure substances can undergo changes in Phase.
solid  liquid: melting
liquid  solid: freezing
liquid  gas: vaporization
gas  liquid: condensation
solid  gas: sublimation
gas  solid: deposition

6. The intensive state of a closed system at equilibrium is its condition as described by the values of its intensive thermodynamic properties.
In this class we will be dealing with simple compressible systems.
Examples of Simple Compressible Systems:
--Standard Air (Oxygen-Nitrogren mix)
--Ideal Gases
--Superheated Water Vapor
For a simple compressible system, specifying any ___2_____ independent intensive thermodynamic properties will fix the other intensive thermodynamics properties of the system.
Intensive Properties include:
Pressure Temperature Density
Specific Volume Internal Energy
Enthalpy Entropy

7. Most important skill for today’s lecture:
Given any two intensive properties of H20, be able to specify other intensive properties.
Given any two of
Temperature
Specific Volume
and Pressure
...find the missing intensive property value. or or

8. Sec 3.2: P-v-T relation
3D p-v-T surface model: A representation of how p, v, and T take on specific values depending upon their intensive properties and phase changes.
The different surfaces of the model represent different phases of a pure substance (like H20) which depend only on the pressure, temperature, and specific volume of the state.

9. Sec 3.2: P-v-T relation
Phase Diagram from the 3D p-v-T surface model: If you pull off the Pressure-Temperature projection you create a plot given as the Phase Diagram.
Triple point •
Critical Point
Temperature
Pressure

10. Sec 3.2: P-v-T relation
p-V Diagram from the 3D p-v-T surface model: The Pressure-Specific Volume projection of the surface model is a useful tool for showing processes involving ice-water-water vapor system.
Specific Vol.
Pressure •

11. Phase diagram p-V Diagram
Sec 3.2: P-v-T relation
Projections of p-v-T surface: Triple Point--the state at which solid, liquid, and gas coexist Critical Point-- the point where saturated liquid and saturated vapor lines meet.
Isotherms--Lines of constant temperature
Isotherms
Phase diagram p-V Diagram

12. Sec 3.2: P-v-T relation
T-v diagram from the 3D p-v-T surface model: If you pull off the Temperature-Specific Volume projection you create a plot that can be useful for showing lines of constant pressure. •
Temperature
Specific Volume
isobar: line of constant pressure

13. You should be able to recognize:
i) Saturated Liquid Line (identified values of Tf , vf, and pf )
ii) Saturated Vapor Line (identified values of Tg , vg, and pg
iii) Critical Point (inflection point at top of dome)
iv) On p-v diagram, lines of constant temperature run from high left to low right.
v) On T-v diagram, lines of constant pressure run from low left to high right.
vi) While traversing the liquid-vapor phase (the area under the dome),
both temperature and pressure remain constant for changes in spec. volume.
Temperature

14. sub-cooled liquid (compressed liquid)
Sec 3.3: Phase Change C
steam
Consider a Constant Pressure Process
Run
Animation
Fig03_03 • •
i j
super
vapor
sat.
vapor
vapor
water
vapor
water
water
water
sub-cooled liquid (compressed liquid)
saturated liquid
two phase
liquid vapor
two phase
liquid-vapor
saturated
vapor
super heated vapor
(steam)

15. Fig03_03 Two Phase, Liquid-Vapor Mix
Sec 3.3: Phase Change
Two Phase, Liquid-Vapor Mix
Can have different mixtures of liquid and vapor (10% liquid, 90% vapor)
Fig03_03
Distinguish mixture of liquid/vapor using quality.
x = 1, saturated vapor (g)
x = 0, saturated liquid (f)
Can also be expressed as a percentage (%)

16. Fig03_03 Two Phase, Liquid-Vapor Mix
Sec 3.5: Saturation
Two Phase, Liquid-Vapor Mix
Quality (x) is also a property. It is a way to express the relative amount of a substance that contains two different phases of material.
Fig03_03
For example, in a given vessel, we know that the two volumes must add to the total volume
with

17. Quantitative Thermodynamic Properties:
Given any two intensive properties, can you
a) determine the phase (liquid, saturated, mixture, solid, or gas?)
b) determine the other intensive property values at that state.
Methods:
1) Read off a p-v or a T-v diagram
2) Look up on Steam Tables: (Appendix and Handout)
i) Table A.2: Prop. of Saturated H20: Temperature Table
ii) Table A.3: Prop. of Saturated H20: Pressure Table
iii) Table A.4: Prop. of Superheated Water Vapor
iv) Table A.5: Prop. of Compressed Water
v) Table A.6: Prop. of Saturated H20: Solid-vapor table
3) Use a Computer Steam Application
i) IT (download from
ii)
pressure
spec. vol. *
(p, v, T)
Link to IT
download
Link to IT
dofmaster

18. Examples of Property Diagrams
Given two properties, locate and read other values.
Molliere chart
Pyschrometric chart

19. Saturated Steam Table Read p and v. Given T= 25 deg C
and saturated vapor
Given two property values, look up other intensive values.

20. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following
Identify the specific volume, v, if possible:
a) p = 5 bar T = deg C.
b) p = 5 bar T = 200 deg. C.
c) p = 2.5 MPa T = 200 deg C.
d) p = 2.8 bar T = 160 deg C.
e) p = 1 bar T = -12 deg C.

21. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following:
Identify the specific volume, v, if possible:
a) p = 5 bar T = deg C.
from table A.3: at 5 bar the saturated temperature is which means
it could be anywhere on the liq-vapor line as a two phase material.

22. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following
Identify the specific volume, v, if possible:
a) p = 5 bar T = deg C.
b) p = 5 bar T = 200 deg. C.
c) p = 2.5 MPa T = 200 deg C.
d) p = 2.8 bar T = 160 deg C.
e) p = 1 bar T = -12 deg C.

23. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following:
b) p = 5 bar T = 200 deg. C.
from table A.3: at 5 bar the temp. of 200 > which means the substance is vapor or superheated vapor…need to consult table A.4
from table A.4 at 5 bar and T = 200 deg C….v = m3/kg

24. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following
Identify the specific volume, v, if possible:
a) p = 5 bar T = deg C.
b) p = 5 bar T = 200 deg. C.
c) p = 2.5 MPa T = 200 deg C.
d) p = 2.8 bar T = 160 deg C.
e) p = 1 bar T = -12 deg C.

25. Example 1: Determine property values
c) p = 2.5 MPa T = 200 deg C.
from table A.3 at 2.5 MPa = 25 bar the temp of 200 is 200< 224 which means that the substance is compressed liquid. For compressed liquid we assume that the spec. vol, will be similar to vf = x10-3. This can be checked on Table A.5 for compressed liquids which gives x10-3 m3/kg

26. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following
Identify the specific volume, v, if possible:
a) p = 5 bar T = deg C.
b) p = 5 bar T = 200 deg. C.
c) p = 2.5 MPa T = 200 deg C.
d) p = 2.8 bar T = 160 deg C.
e) p = 1 bar T = -12 deg C.

27. Example 1: Determine property values
d) p = 2.8 bar T = 160 deg C.
from Table A.2 at Tsat = 160, psat = > which means the substance will be vapor or superheated…so refer to table A.4.
from Table A.4 at p = 1.5 and T = 160….v = 1.317
at p = 3 and T = 160….v = 0.651
Interpolation is required:

28. Example 1: Determine property values
Determine phase or phases of H20 at the following conditions and sketch p-v and T-v diagrams showing the positions of each of the following
Identify the specific volume, v, if possible:
a) p = 5 bar T = deg C.
b) p = 5 bar T = 200 deg. C.
c) p = 2.5 MPa T = 200 deg C.
d) p = 2.8 bar T = 160 deg C.
e) p = 1 bar T = -12 deg C.

29. Example 1: Determine property values
e) p = 1 bar T = -12 deg C.
from table A.3 at psat of 1 bar, Tsat = C > -12 which means the substance will be compressed liquid or solid. Noticing that Table A-5 doesn’t handle pressures this low, if you assumed that the material was liquid, you would use the saturated spec. vol. at the given temperature of -12 deg. However, you recognize that -12 degrees is below the freezing point of water and therefore you expect that this is in solid phase (ice).
Table A-6 also has information on saturated solid-vapor data.
Assume v = vi for a T of -12 deg. C v = x 10-3 = m3/kg

30. Linear Interpolation:* y2
yunknown
xknown x1 y1 x2

31. Linear Interpolation will be needed. Given the following:
Sec 3.5: Evaluating P, v, T
You try it: What is the specific volume of a water at 40 bar and 140 oC?
Linear Interpolation will be needed.
Given the following:
@ 140°C & 25 bar, v1 = m3/kg
@ 140°C & 50 bar, v2 = m3/kg
Find the spec. vol at p = 40 bar.

32. This time try it for the same pressure with different temperatures.
Sec 3.5: Evaluating P, v, T
Example 2:
This time try it for the same pressure with different temperatures.
Given:
40 bar and 180 oC, the specific volume of water is m3/kg.
40 bar and 140 oC, the specific volume of water is m3/kg.
What is the specific volume of water at 40 bar and 150 oC?
@ 180°C & 40 bar, v1 = m3/kg

33. Sec 3.5.2 : Saturation Tables
Example:
A cylinder-piston assembly initially contains water at 3 MPa and 300oC. The water is cooled at constant volume to 200 oC, then compressed isothermally to a final pressure of 2.5 MPa. Sketch the process on a T-v diagram and find the specific volume at the 3 states.

34. Sec 3.5.2 : Saturation Tables
Example:
TV diagram

35. State 1: p1 = 3 MPa= 30 bar and T1 = 300 deg C.
i) Start with superheated vapor table A-4
ii) Interpolate between 280 and 320 deg C.

36. State 2: v2 = v1 = 0.0811 m3/kg and T2 = 200 deg C.
Recognize that this is in the liquid-vapor mixture range.
Refer to Table A-2
i) Locate vg and vf at T = 200 deg C.
ii) Determine quality, x2

37. p3 = 2.5 MPa = 25 bar and T2 = T3= 200 deg C.
State 3:
p3 = 2.5 MPa = 25 bar and T2 = T3= 200 deg C.
Recognize that this is in the compressed liquid.
Refer to Table A-5
i) Locate p3=25 bar and T3=200 deg C
ii) Read the value of v directly.

38. End of Slides for Lecture 06